International Construction Law Review
THE QUANTIFICATION OF UNJUST ENRICHMENT CLAIMS IN CONSTRUCTION
Dr Franco Mastrandrea
Chartered Quantity Surveyor and Chartered Arbitrator
INTRODUCTION
The broad objective of the law of restitution is to prevent unjust enrichment. Thus, the US Restatement, Restitution,1 §1, provides:
“… a person who has been unjustly enriched at the expense of another is required to make restitution to the other.”
Unjust enrichment is the foundation for the restitutionary remedy, designed to reverse that enrichment, whether by way of the return of money,2 or payment for goods3 or services.4
Dispute resolvers applying modern English law must ask themselves the following four questions when faced with a claim for unjust enrichment:5
- (a) Has the defendant been enriched?
- (b) Was the enrichment at the claimant’s expense?
1 The original Restatement (whose full title was Restitution, Quasi-Contracts and Constructive Trusts), extended to more than restitution for unjust enrichment. The current, Third, Restatement, Restitution
and Unjust Enrichment
(2011), formulation of §1 remains in identical terms as the original.
(Emphasis supplied.)
2 Historically at common law, by means of the form of action for money had and received.
It is rarely the case in construction claims that the parties are arguing about the return of liquid
forms of money, and the niceties that can emerge with such claims (such as where the money may have been stolen).
3 By means, traditionally, of a claim for restitutionary quantum meruit. The term quantum meruit has been much misused. A distinction should clearly be drawn between a contractual quantum meruit and the term as used here in the unjust enrichment or restitutionary sense: see, Lord Burrows, dissenting, in Barton and Others v Morris and Another (SC) [2023] UKSC 3; [2023] AC 684; [2023] 2 WLR 269, especially at paragraph 204.
4 By means, traditionally, of a claim for quantum valebat. Quantum meruit and quantum valebat are often used collectively or interchangeably, with quantum meruit being typically used for both.
5 See Benedetti v Sawiris and Others (SC) [2013] UKSC 50; [2014] 1 AC 938; [2013] 3 WLR 351; [2013] 4 All ER 25; 149 Con LR 1, per Lord Clarke at paragraph 11.
Cf. Banque Financiére de la Cité v Parc (Battersea) Ltd and Others (HL) [1999] 1 AC 221, [1998] 2 WLR 475; [1998] 1 All ER 737, per Lord Steyn at paragraph 227; Bank of Cyprus UK Ltd v Menelaou (SC) [2015] UKSC 66; [2016] AC 176; [2015] 3 WLR 1334, per Lord Clarke at paragraph 18; The Commissioners for Her Majesty’s Revenue and Customs v The Investment Trust Companies (SC) [2017] UKSC 29; [2018] AC 275; [2017] 2 WLR 1200; [2017] 3 All ER 113, per Lord Reed at paragraph 41, pointing out that these were not legal tests but signposts towards areas of inquiry, involving a number of distinct legal requirements; Barton and Others v Morris and Another (SC) [2023] UKSC 3; [2023] AC 684; [2023] 2 WLR 269, per Lady Briggs at paragraph 77 and per Lord Burrows at paragraph 228; Samsoondar v Capital Insurance Ltd (PC) [2020] UKPC 33; [2021] 2 All ER 1105, per Lord Burrows at paragraph 18; Attorney General of Trinidad and Tobago v Trinsalvage Enterprises Ltd (PC) [2023] UKPC 26, per Lord Burrows at paragraph 18.
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